The clinical significance of stool isolates of aeromonas

The purpose of this study was to determine the clinical significance of different Aeromonas species isolated from stool. During a 17-month period, 29 strains of Aeromonas were isolated and identified to species with the following results: 22, A. caviae, 5, A. hydrophila, and 2, A. sobria. Clinical significance was determined independently of knowledge of speciation result. Nineteen isolates represented colonization, implying that Aeromonas can be recovered from the gastrointestinal tract without causing primary disease. The remaining 10 isolates were of indeterminate significance and may have played a role in infection, but pertinent tests to rule out other enteric pathogens had not been done. A correlation between species and clinical significance could not be established. Antimicrobial susceptibility testing was performed on the 29 isolates. A. caviae showed an unexpected resistance to cefazolin and cefoxitin, whereas representatives of all three species displayed resistance to trimethoprim/sulfamethoxazole.     

Proposed interpretive criteria and quality control parameters for ofloxacin susceptibility testing of Neisseria gonorrhoeae.

A multilaboratory study designed to determine the in vitro susceptibility criteria and quality control parameters for ofloxacin against Neisseria gonorrhoeae was conducted according to the guidelines of the National Committee for Clinical Laboratory Standards. Proposed susceptibility breakpoints are MICs of less than or equal to 0.25 microgram/ml for the agar dilution test and greater than or equal to 31 mm for the disk diffusion test. A category for resistance could not be defined. Proposed acceptable quality control MICs for N. gonorrhoeae ATCC 49226 and Staphylococcus aureus ATCC 29213 range from 0.004 to 0.03 microgram/ml and 0.25 to 1.0 microgram/ml, respectively. With 5-micrograms ofloxacin disks, acceptable inhibitory zone diameters for S. aureus ATCC 25923 and the N. gonorrhoeae control strains range from 22 to 27 mm and 43 to 51 mm, respectively.     

Hoechst staining and exposure to UV laser during flow cytometric sorting does not affect the frequency of detected endogenous DNA nicks in abnormal and normal human spermatozoa

Controlling the sex of offspring by the separation of X and Y chromosome-bearing spermatozoa using flow cytometry has been reported as a clinical technique aiding prevention of X-linked diseases. Although this technique has resulted in several hundred normal births in animals and at least one human birth, there is still concern over its genetic safety due to the involvement of two potentially mutagenic agents: UV light and the fluorochrome dye, Hoechst 33342 (H33342). Human spermatozoa, particularly those considered abnormal, may be more likely to suffer DNA damage following exposure to mutagenic agents, compared with other mammalian species. The stability of normal fresh and decondensed human spermatozoa were examined after exposure to a range of levels of UV and H33342 staining, using an assay that detects endogenous nicks in the DNA of spermatozoa. The stability of abnormal and normal, fresh and frozen-thawed human spermatozoa was examined following UV laser, H33342 staining and flow cytometry treatments utilizing the same assay. There was an increase in the presence of endogenous nicks when spermatozoa were decondensed compared with fresh spermatozoa. There was no increase in the incidence of nicks in any group of spermatozoa after UV and fluorochrome exposure compared with controls without exposure.      

Modulation of disease severity of dystrophic epidermolysis bullosa by a splice site mutation in combination with a missense mutation in the COL7A1 gene

Dystrophic epidermolysis bullosa (EBD) is a clinically heterogeneous skin disorder, characterized by abnormal anchoring fibrils (AF) and loss of dermal-epidermal adherence. EBD has been linked to the COL7A1 gene at chromosome 3p21 which encodes collagen VII, the major component of the AF. Here we investigated two unrelated EBD families with different clinical phenotypes and novel combinations of recessive and dominant COL7A1 mutations. Both families shared the same recessive heterozygous 14 bp deletion at the exon-intron 115 boundary of the COL7A1 gene. The deletion caused in-frame skipping of exon 115 and the elimination of 29 amino acid residues from the pro-alpha1(VII) polypeptide chain. As a result, procollagen VII was not converted to collagen VII and the C-terminal NC-2 propeptide which is normally removed from the procollagen VII prior to formation of the anchoring fibrils was retained in the skin. All affected individuals also carried missense mutations in exon 73 of COL7A1 which lead to different glycine- to-arginine substitutions in the triple-helical domain of collagen VII. Combination of the deletion mutation with a G2009R substitution resulted in a mild phenotype. In contrast, combination of the deletion with a G2043R substitution led to a severe phenotype. The G2043R substitution was a de novo mutation which alone caused a mild phenotype. Thus, different combinations of dominant and recessive COL7A1 mutations can modulate disease activity of EBD and alter the clinical presentation of the patients.      

Detection of extended-spectrum-beta-lactamase-producing members of the family Enterobacteriaceae with Vitek ESBL test.

A three-phase analysis of the Vitek ESBL test and a double-disk (2 disk) test was performed to assess their ability to detect extended-spectrum beta-lactamases (ESBLs) in members of the family Enterobacteriaceae. In the first two phases involving detection of ESBLs in 157 stains processing well-characterized beta-lactamases, sensitivity and specificity were found to be 99.5 and 100%, respectively, for the Vitek ESBl test and 98.1 and 99.4%, respectively, for the 2-disk test. In the third phase, in which the ability of each test to detect ESBLs in 295 clinical isolates was assessed, there was only one false positive (Vitek ESBL test). Across all three phases, the Vitek ESBL test was found to be much easier to perform than the 2-disk test. The latter also involved subjective interpretation of results. There were a total of 176 Escherichia coli and 157 Klebsiella pneumoniae isolates and less than 40 isolates of each of 14 other species evaluated. In a supplemental study of Klebsiella oxytoca, an organism possessing a chromosomal beta-lactamase similar to an ESBL, the Vitek ESBL test was found to be capable of detecting hyperproduction of this enzyme in strains of this species as well. These data indicate that the Vitek ESBL test is reliable for the detection of ESBLs in E. coli and K. pneumoniae, the two species in which ESBLs are most common, and of hyperproduction of the K. oxytoca beta-lactamase, a situation which engenders a level of resistance to this species similar to that seen with ESBLs.     

CD4+ lymphocytes are extracted from blood by peripheral lymph nodes at different rates from other T cell subsets and B cells

The circulation of lymphocyte subsets through prescapular lymph nodes in sheep has been quantified using a panel of monoclonal antibodies against sheep lymphocyte surface antigens. Differences in the extraction of lymphocyte subsets from blood by the lymph node were found with CD4+ lymphocytes being extracted at a faster rate (1/2) than CD8+, SBU-T19+, major histocompatibility complex class II+ and B cells (1/4 to 1/5). In order to accommodate existing data on organ-specific adhesion molecules, one subset specific and one tissue specific, expressed on vascular endothelium could act jointly to regulate the migration of recirculating lymphocytes.